Conveyor belt system

ABSTRACT

A system is disclosed for controlling the discharge of articles from a steel belt conveyor. When articles are placed on the belt at the loading station, the belt is magnetized at a high intensity in a very small area which has a predetermined relationship, longitudinally of the belt, to the position of the article on the belt. The magnetized spot is also positioned transversely of the belt in accordance with the station where the article is to be discharged. At each discharge station there is an arrangement in the form of a plow and means to move the plow to and from the path of articles carried on the belt so as to deflect the articles from the belt. The plow operating mechanism has an electronic control which includes a Hall-effect transducer positioned adjacent the bottom surface of the belt and relatively positioned transversely of the belt along the path of the magnetized spots for that station. Hence, when an article is placed on the belt and the magnetized spot is produced corresponding to a particular unloading station. The article will be carried to that station and unloaded. The high intensity magnetization is produced by an electromagnet extending transversely from the bottom surface of the belt, and direct current is supplied to the electromagnet coil from a condenser circuit. The current can be caused to flow in either direction through the coil so as to produce a magnetized zone or spot of either north or south polarity. The magnetized zone or spot is surrounded by a ring of the opposite polarity but of insufficient intensity to energize the Hall-effect control unit. The number of discharge stations may be increased by producing two or more magnetized spots for various of the discharge stations.

United States Patent Alfredsson [451 May 30,1972

[73] Assignee:

[54] CONVEYOR BELT SYSTEM Stlg Allan Junior Alfredss'on, Sandviken,Sweden [72]- Inventor:

22 Filed: Nov. 14, 1969 211 App1.No.: 876,967

[30] Foreign Application Priority Data Apr. 28, 1969 Sweden ..5979/69324/45' [51 Int. Cl ..B65g 43/00 [58] Field of Search ..198/38, 188, 81;324/45 [56] I References Cited UNITED STATES PATENTS 3,173,533 3/1965Zuck ..198/38 3,084,784 4/1963 Zoubek 198/38 2,784,851 3/1957Bretschneider.. .198/38 UX 3,219,909 11/1965 Foster ....324/45 X3,019,385 l/1962 Kalbfell .198/38 UX 3,275,123 9/1966 Prosser et al...198/38 3,214,003 10/1965 Wilson ..198/38 Primary Examinerl-larvey C.Hornsby Assistant Examiner-Merle F. Maffei Attorney-Curtis, Morris &Safford 57 ABSTRACT A system is disclosed for controlling the dischargeof articles from a steel belt conveyor. When articles are placed on thebelt at the loading station, the belt is magnetized at a high intensityin a very small area which has a predetermined relationship,longitudinally of the belt, to the position of the article on the belt.The magnetized spot is also positioned transversely of the belt inaccordance with the station where the article is to be discharged. Ateach discharge station there is an arrangement in the form of a plow andmeans to move the plow to and from the path of articles carried on thebelt so as to deflect the articles from the belt. The plow operatingmechanism has an electronic control which includes a Hall-effecttransducer positioned adjacent the bottom surface of the belt andrelatively positioned transversely. of the belt along the path of themagnetized spots for that station. Hence, when an article is placed onthe belt and the magnetized spot is produced corresponding to aparticular unloading station. The article will be carried to thatstation and unloaded. The high intensity magnetization is produced by anelectromagnet extending transversely from the bottom surface of thebelt, and direct current is supplied to the electromagnet coil from acondenser circuit. The current can be caused to flow in either directionthrough the coil so as to produce a magnetized zone or spot of eithernorth or south polarity. The magnetized zone or spot is surrounded by aring of the opposite polarity but of insufficient intensity to energizethe Hall-effect control unit. The number of discharge stations may beincreased by producing two or more magnetized spots for various of thedischarge stations.

7 Claims, 6 Drawing Figures Patented May 30, 1972 3,666,080

2 Sheets-Sheet INVENTOR:

STIG ALLAN JUNIOR ALFREDSSON Attorneys Patented May 30, 1972 3,666,080

2 Sheets-Sheet 2;

Fig.3 L a v L10 r- 23.

INVENTOR STIG ALLAN JUNIOR ALFREDSSON Cmfik, flkmwfij/slf/zd AttorneysCONVEYOR BELT SYSTEM This invention relates to steel belt conveyorsystems for carrying products from a loading station to deliverystations. The invention relates particularly to systems for controllingthe discharge of various products at selected stations along the path ofthe steel belt conveyor.

An object of this invention is to provide-for the efficient anddependable delivery of products from a loading station to variousselected discharge stations. A further object is to provide an improvedsystem for controlling steel belt conveyors. A further object is toprovide improved means for producing magnetized areas or zones in aconveyor and for utilizing such areas or zones for controlling theconveyor operations. These and other objects will be in part obvious andin part pointed out below.

FIG. 1 is a side view of a conveyor belt system according to the presentinvention{ FIG. 2 is a plan view of the apparatus of FIG. 1;

FIG. 3 is a diagrammatic view, partly in block schematic form, of themagnetization portion of the apparatus according to the presentinvention;

FIG. 4 is a graph of the magnetization current of the ap paratus of FIG.3;

FIG. 5 is a graph of the output voltage of the Hall-effect transducerportion of the apparatus according to the present invention; and

FIG. 6 is a diagrammatic view, partly in block schematic form, of thedetection portion of the apparatus according to the present invention.

Referring initially to FIGS. 1 and 2, the operation 30 of a conveyorbelt system according to the present invention will now be explained bydescribing, in sequence, the transportation of an article from receiptto delivery. A steel conveyor belt 10 is rotatably mounted on rollers 11and 12 which are rotated in clockwise direction, indicated by arrow 13,in a conventional manner, so that an article 15, placed upon belt 10,will be transported along the path of belt 10, in the directionindicated by arrow 50. Disposed along the path of, and adjacent to, belt10 are a plurality of receiving stations, only one of which, receivingstation 24, is shown, for selectively receiving the articles transportedby the conveyor belt system.

Initially, article 15 is placed upon belt 10 at a location near rollerl1.-At or before this time, the operator selects the desired receivingstation, for example, receiving station 24, for the particular article15 by feeding this information into a control panel 17. This may beaccomplished by providing control panel 17 with a plurality of pushbuttons or switches, each one corresponding to a particular receivingstation, which may be operated to select the appropriate receivingstation, or this may be accomplished by other conventional means.

A plurality of electromagnets 14a, 14b, and 14c are disposed in atransverse row beneath belt 10 at a distance along the path of belt 10from roller 11. A lamp 26 and a photocell 27 are located at oppositesides of, and above the surface of belt 10, between roller 11 andelectromagnets 14a, 14b, and 140. Lamp 26 and photocell 27 are suitablyoriented so that the light beam from lamp 26 will impinge upon photocell27. Photocell 27, control panel 17, and electromagnets 14a, 14b, and 14care interconnected so that one of the electromagnets 14a, 14b, or 140will be momentarily energized when article 15 interrupts the path of thelight beam from lamp 26 to photocell 27. The particular electromagnetwhich is energized will correspond with the particular desired receivingstation. For example, electromagnet 14a will be energized to obtain thedelivery of article 15 to receiving station 24.

The momentary energization of electromagnet 14a results in the creationof a magnetized spot or zone 20 in belt 10. Magnetized spot 20 islocated a distance in front of article 15 corresponding to the distancebetween lamp 26 and photocell 27 and electromagnets 14a, 14b, and 140. Aplurality of magnetic spot detectors, 21a and 21b, of which two areshown, each of which corresponds to a particular receiving station,

are located beneath belt 10. Each magnetic spot detector is located infront of its associated receiving station at a distance from the edge ofbelt 10 corresponding to the distance from the edge of belt 10 to theelectromagnet associated with the particular receiving station. Forexample, magnetic spot detector 21a is located in front of receivingstation 24, at a location from the edge of belt 10 corresponding to thelocation of electromagnet 14a. Magnetic spot 20 will thus pass overmagnetic spot detector 21a as belt 10 proceeds along its path.

A pivotable arm or member 16 is located at each receiving station. Apivoting mechanism 22 is connected to arm 16. When energized, pivotingmechanism 22 will cause arm 16 to pivot so that it will align itselfdiagonally with, and above the surface of, belt 10, causing article 15to be deflected from belt 10 to receiving station 24. Magnetic spotdetector 21a is suitably interconnected with pivoting mechanism 22 sothat magnetic spot 20 will cause member 16 to pivot into position in thepath of article 15 for an appropriate time to produce the discharge ofarticle 15 onto receiving station 24.

After article 15 has been deposited at receiving station 24, arm 16 iscaused to move back to its original position by pivoting mechanism 22.Magnetic spot 20 will remain in belt 10 until such time as it passesover one of a plurality of de-magnetizing coils 23a, 23b, or 23c,energized by AC line current, which are located beneath belt 10, betweenthe receiving stations and photocell 27 and lamp 26. Magnetic spot 20will thus be de-magnetized, thus returning the system to its initialcondition.

In order to increase the number of receiving stations which may becontrolled by electromagnets 14a, 14b, and 14c, electromagnets 14a, 14b,and 14c may be energized so as to produce a magnetized spot of either ofnorth or south polarity. Magnetic spot detectors which are sensitive toonly one magnetic polarity may then be provided so that a singleelectromagnet 14a, 14b, or 14c may be used to control the discharge ofarticles at two receiving stations. The number of receiving stationswhich may be controlled will thus be twice the number of electromagnets.Furthermore, by placing more than one magnetic spot detector at certainof the receiving stations, the number of possible receiving stationswhich can be controlled by a given number of electromagnets may befurther increased by requiring a particular combination of magneticspots to energize the particular receiving station.

Referring to FIG. 3, the operation of one of the electromagnets l4a,14b, or will now be explained. The object of each electromagnet 14a,14b, 140 is to produce a magnetized spot on belt 10 which is asconcentrated and distinct as possible. For this purpose, electromagnet14a, 14b, or 14c comprises a magnetizable soft iron core 30 locatedbeneath belt 10, at a small distance therefrom. Core 30 is alignedperpendicular to belt 10 to produce optimum concentration of themagnetic field on belt 10. Core 30 may be made of laminated soft iron orother suitable material. Wound about core 30 is a solenoid or coil 31.Energization of coil 31 will produce a magnetic field, indicated byfield lines 51, which will enter belt 10 in a concentrated area and willexit belt 10 with reversed polarity dispersed in the surrounding area.If coil 31 is energized by a pulse of sufiicient magnitude to producesaturation, a magnetized spot of high intensity will be created in belt10, surrounded by a larger diffused area of opposite magnetic polarity.The shape of the magnetized spot will depend upon the shape of core 30.Thus, to produce a circular magnetic spot core 30 should be cylindricalin form. However, it may be desirable to produce a magnetic spot whichis elongated in the transverse direction of belt 10 in order to enablethe spot to impinge upon the corresponding magnetic spot detectorregardless of the possible side movement of belt 10. To produce thisresult, core 30 may be of rectangular cross-section aligned with itslonger dimension transverse to the direction of belt 10. The magneticpolarity of the magnetized spot is dependent upon the direction ofcurrent flow through coil 31. Thus a single coil may be used to producemagnetic spots of either north or south polarity.

Referring to FIG. 4, the desirable current through coil 31 I is shownwith respect to time I. By so energizing coil 31 with a pulse havingsharply defined leading and trailing edges, a high intensity, distinctmagnetic spot will be produced on belt 10.

Returning to FIG. 3, the circuitry associated with coil 31 for producingsuch a magnetizing current I will now be explained. Prior toenergization of coil 31, the operator depresses one of the momentarycontact switches 70. This causes one of the flip-flops 71 to changestate. The circuit is thereby conditioned to energize the electromagnet14a, 14b, or 140 and is prevented from accepting additional inputinformation by a lock-out circuit 72 which supplies the voltage to themomentary contact switches 70. Connected to the outputs of flip-flops 71are a pair of And gates 73. The output of photocell 27 is amplified byan amplifier 74 and conducted to a monostable multivibrator 75. When thearticle interrupts the path of the light beam from lamp 26 to photocell27, monostable 75 is caused to change state. The output of monostable 75is connected to And gates 73 so that an output will appear at theparticular And gate 73 associated with the momentary contact switch 70which was depressed. The outputs of AND gates 73 are connected to aswitching means 77 which connects a capacitor 76, which has beenpreviously charged to a DC voltage, to coil 31. The direction of thecurrent flow through coil 31 is dependent upon the particular AND-gate73 which produces output voltage and is thus determined by theparticular momentary contact switch 70 that was depressed. Chargedcapacitor 76 will discharge through coil 31 in accordance with the RLCtime constant of coil 31, capacitor 76 and switch means 77 so as toproduce a magnetic current I which will approximate the desired magneticcurrent I depicted in FIG. 4. To insure substantial discharging ofcapacitor 76, the RLC time constant is shorter than the period of timeduring which capacitor 76 is connected to coil 31, corresponding to thetime during which monostable 75 is in its activated state. In addition,the outputs of AND-gates 73 serve to reset flip-flops 71, thus returningthe circuit to its initial condition. Of course, coil 31 may beenergized in an alternate conventional manner.

Referring to FIG. 6, the operation of the magnetic spot detector willnow be explained. The magnetic spot detector 21a or 21b comprises aHall-effect generator 41 located a small distance below belt 10. A core40 of magnetizable material is disposed below Hall-effect generator 41in an alignment similar to the alignment of core 30. Core 40 serves toconcentrate the magnetic field of the magnetized spot throughHallefi'ect generator 41. In effect, the magnetic field lines associatedwith the magnetized spot will be directed by core 40 in directionssimilar to the magnetic field produced by electromagnet 14a, 14b, 14c.The Hall-effect generator consists of a conductor aligned perpendicularto the magnetic field of the magnetized spot through which a directcurrent is supplied by a direct current source 60, through input leads61. When the magnetized spot is present above the Hall-effect generator41, a voltage will be induced in the conductor which is perpendicular toboth the direction of current flow through the conductor and thedirection of the magnetic field. This voltage is dependent in amplitudeand polarity upon the field strength and magnetic polarity of themagnetized spot. The voltage produced by the Hall-effect generator isconducted to an amplifier 63 through a pair of output leads 62.

FIG. shows the output voltage E of the Hall-effect generator withrespect to time t. As the magnetized spot passes above Hall-effectgenerator 41, a voltage of one polarity having an amplitude X2 will beproduced by the dispersed magnetic field surrounding the magnetizedspot. When the magnetized spot passes directly over Hall-effectgenerator 41, voltage of opposite polarity having an amplitude of X1will be produced. Similarly, as the spot passes beyond Hall-effectgenerator 41, an output voltage of the initial polarity having anamplitude similar to amplitude X2 will again be produced. Since themagnetic field strength of the magnetized spot is substantially greaterthan the magentic field strength of the surrounding dispersed magneticarea, the amplitude X1 will be substantially greater than the amplitudeX2.

In order to provide for magnetic spot detectors which are responsive toonly one magentic polarity, so as to enable a single electromagnet tocontrol the operation of two receiving stations, the direction ofcurrent flow through the Hall-effect generator may be reversed in thoseHall-effect generators which are to react to the opposite magneticpolarity, so that output voltages of similar polarity will be producedby all of the Hall-effect generators when the appropriate magneticfields are present. This enables the use of identical associatedcircuitry with all of the Hall-effect generators.

Returning to FIG. 6, the output voltage E of the Hall-effect generatoris amplified by amplifier 63 and is conducted to a comparator cirucit64, which is suitably constructed so as to produce an output signal onlyupon receipt of an input signal of appropriate amplitude associated withthe portion of the output voltage E produced by the magnetic spot. Inthis manner, the effects of stray magnetic fields present in belt 10 orthe surrounding vicinity will be substantially eliminated. The output ofcapacitor circuit 64 is conducted to a monostable multivibrator whichwill produce a signal of appropriate duration to energize pivotingmechanism 22 for an appropriate period of time required for the deliveryof the article to the receiving station.

The above description of the invention is intended to be illustrativeand not limiting. Various changes or modifications in the embodimentsdescribed may occur to those skilled in the art, and these can be madewithout departing from the spirit or scope of the invention as set forthin the claims.

What is claimed is:

1. In a conveyor system, the combination of, a steel belt conveyorhaving a load carrying run extending from a loading station along a pathwhich passes a plurality of discharge stations, magnetic means at saidloading station to produce discrete magnetized zones of high intensityand of single polarity in said belt with the magnetic field extendingperpendicular to the belt surfaces with each zone having a selectedposition with respect to one edge of said belt, and discharge controlmeans including detector means for each of said discharge stations, saiddetector means including a Hall-effect transducer positioned to detectonly the perpendicularly extending magnetic field of said magnetizedzones, said control means being operative to discharge products fromsaid belt at a particular one of said discharge stations in accordancewith the respective detection of magnetized zones.

2. In a conveyor system, the combination of, an endless steel belthaving a run extending from a loading station along a path which passesa plurality of discharge stations, magnetizing means for said loadingzone to produce discrete magnetized signal zones each of which comprisesa high intensity magnetized zone of single polarity with the magneticfield extending perpendicular to the belt surfaces and a zone ofsubstantially lesser magnetic intensity radially outwardly from saidhighly magnetized zone, said highly magnetized zone having a selectedposition with respect to one edge of said belt, and discharge meansincluding means at each of said discharge stations including detectormeans which is positioned with respect to said edge of said belt so asto be responsive to only the perpendicularly extending magnetic field ofone of said high intensity magnetic zones and control means responsiveto said detector means to discharge products at each of the dischargestations in accordance with the respective detection of high intensitymagnetized zones.

3. A system as described in claim 2 wherein said magnetizing meansproduces circular high intensity magnetizing zones.

4. A system as described in claim 2 wherein said detector meanscomprises a Hall effect transducer positioned adjacent to the bottomsurface of said belt.

5. In a conveyor system, the combination of an endless conveyor belthaving the characteristics that it is magnetizable and positioned with aconveying run extending from a loading station along a path which passesa plurality of discharge stations, magnetizing means for said loadingstation to produce discrete magnetized signal zones in the belt each ofwhich comprises a magnetic field of single polarity extendingperpendicular to the belt surfaces, each of said magnetized zones havinga selected position with respect to one edge of the belt and a positionlongitudinally of the belt relative to the material which is beingcarried by the belt along said conveying run, and discharge means forthe materials including means at each of said discharge stations todischarge the material and detector means which is responsive only tothe perpendicularly extending magnetic field of each magnetized zone andcontrol means to operate said discharge means in response to a signalreceived from said detector means.

6. A conveyor system as described in claim 5 wherein said belt is ofsteel and wherein said magnetizing means and said detector means arepositioned beneath said belt along said conveying run.

7. The method of controlling the delivery of products from a steel beltconveyor which comprises the steps of, magnetizing a discrete spot onthe belt with a high intensity magnetic field extending perpendicular tothe belt surfaces within a zone at a predetermined distance from a sideedge of the belt which has been designated to correspond with aparticular discharge station, detecting the arrival of only theperpendicularly extending magnetic field of the spot at said dischargestation by a Hall-effect transducer positioned adjacent the bottomsurface of the belt, and removing the product from the belt at saiddischarge station in response to the signal produced by said Hall-effecttransducer.

1. In a conveyor system, the combination of, a steel belt conveyorhaving a load carrying run extending from a loading station along a pathwhich passes a plurality of discharge stations, magnetic means at saidloading station to produce discrete magnetized zones of high intensityand of single polarity in said belt with the magnetic field extendingperpendicular to the belt surfaces with each zone having a selectedposition with respect to one edge of said belt, and discharge controlmeans including detector means for each of said discharge stations, saiddetector means including a Hall-effect transducer positioned to detectonly the perpendicularly extending magnetic field of said magnetizedzones, said control means being operative to discharge products fromsaid belt at a particular one of said discharge stations in accordancewith the respective detection of magnetized zones.
 2. In a conveyorsystem, the combination of, an endless steel belt having a run extendingfrom a loading station along a path which passes a plurality ofdischarge stations, magnetizing means for said loading zone to producediscrete magnetized signal zones each of which comprises a highintensity magnetized zone of single polarity with the magnetic fieldextending perpendicular to the belt surfaces and a zone of substantiallylesser magnetic intensity radially outwardly from said highly magnetizedzone, said highly magnetized zone having a selected position withrespect to one edge of said belt, and discharge means including means ateach of said discharge stations including detector means which ispositioned with respect to said edge of said belt so as to be responsiveto only the perpendicularly extending magnetic field of one of said highintensity magnetic zones and control means responsive to said detectormeans to discharge products at each of the discharge stations inaccordance with the respective detection of high intensity magnetizedzones.
 3. A system as described in claim 2 wherein said magnetizingmeans produces circular high intensity magnetizing zones.
 4. A system asdescribed in claim 2 wherein said detector means comprises a Hall effecttransducer positioned adjacent to the bottom surface of said belt.
 5. Ina conveyor system, the combination of an endless conveyor belt havingthe characteristics that it is magnetizable and positioned with aconveying run extending from a loading station along a path which passesa plurality of discharge stations, magnetizing means for said loadingstation to produce discrete magnetiZed signal zones in the belt each ofwhich comprises a magnetic field of single polarity extendingperpendicular to the belt surfaces, each of said magnetized zones havinga selected position with respect to one edge of the belt and a positionlongitudinally of the belt relative to the material which is beingcarried by the belt along said conveying run, and discharge means forthe materials including means at each of said discharge stations todischarge the material and detector means which is responsive only tothe perpendicularly extending magnetic field of each magnetized zone andcontrol means to operate said discharge means in response to a signalreceived from said detector means.
 6. A conveyor system as described inclaim 5 wherein said belt is of steel and wherein said magnetizing meansand said detector means are positioned beneath said belt along saidconveying run.
 7. The method of controlling the delivery of productsfrom a steel belt conveyor which comprises the steps of, magnetizing adiscrete spot on the belt with a high intensity magnetic field extendingperpendicular to the belt surfaces within a zone at a predetermineddistance from a side edge of the belt which has been designated tocorrespond with a particular discharge station, detecting the arrival ofonly the perpendicularly extending magnetic field of the spot at saiddischarge station by a Hall-effect transducer positioned adjacent thebottom surface of the belt, and removing the product from the belt atsaid discharge station in response to the signal produced by saidHall-effect transducer.